The Castle of Kyparissia is also known as the Giants' Castle or the Castle of Arcadia. Due to its location, it offers the visitor a unique view, not only to the city of Kyparissia (which is 67 km from Kalamata) but also to the entire surrounding area and the Ionian Seashores. Modern scholars, based on its construction, believe that the current surviving castle is mainly Frankish, as such buildings started appearing after 1204/1205. The castle is built higher than the ancient Kyparissienta citadel and the ruins of earlier fortresses (ancient and Byzantine).
According to mythology, Kyparissia was built by "Giants", who are said to have also made the citadel, on which the castle is located today. In other words, it is founded on "cyclopean" walls, with huge boulders, hence the name "the Giants’ Castle".
During the years of the Byzantine Empire, the castle was renovated as part of the organisation of solid defensive shielding of coastal areas. Specifically, fortresses were built at the four corners, one of which (on the east side) is preserved and is known as the "Tower of Justinian". During the Early Byzantine period, Kyparissia is referred to as Arcadia (due to the many Arcadians who took refuge there). Since then, the old Giants’ Castle has been referred to as the Castle of Arcadia.
During the first decades of the 13th century, the castle was dominated by the Venetians and the Franks. From 1430, it became part of the Despotate of Moreas under the control of the Palaeologians as Byzantine. In 1459, it passed into the hands of the Turks, who carried out additional fortifications. During the second Venetian period (1685-1715), the Venetians rebuilt the demolished parts of the castle (towers and ramparts) that the Turks had blown up. The castle was finally liberated by the Greeks, without a fight, on March 25th, 1821. In 1970, a small open-air theatre was built inside the castle, where cultural events and theatrical performances occur.
The castle’s floor plan has a trapezoidal shape, which researcher Antoine Bon divided into two triangles. The northern triangle corresponds to the upper precinct or the "Upper Castle" and the southern to the lower precinct or "Lower Castle". The access to the castle was made by an embankment (ramp) which, in the part closest to the gate, was protected by a wall with loopholes. The lower part of the masonry is preserved up to the height of the ground and is built of ancient boulders (tufa stones). The rest of the walls are built with small alabaster and limestone mixed with pieces of tiles and mortar - a characteristic form of medieval construction.
Finally, in 2007 a rescue excavation was carried out in the western foothills of the castle where the foundations of a building (probably a house) were discovered. The oldest phase of the construction dates back to the Late Hellenistic and Early Roman times (1st-century BC-1st century), while it seems that it continued to be in use until the Late Roman era (3rd-4th century).